Disposable, one-time use pipettes and micro-containers have been standard in the bio-molecular community for some time. They provide an easy and efficient way to obtain sterile conditions and eliminate cross-contamination between cultures and nutrient medium. More recently, the pharmaceutical and biotechnology industries have begun to apply the same principle to larger equipment, and begun making and using disposable, one-use sterile bioreactors, mixers and containers of up to 1000 liters capacity.
A bioreactor, or mixer, is a container with multiple ports for adding and removing ingredients and with a mechanism for agitating the ingredients within the container. The containers are typically available in three forms often referred to as hard shell, soft shell and a combination of hard and soft shell. A hard shell container holds its shape without support or internal pressure and is typically made of material such as, but not limited to, stainless steel or rigid plastics such as polycarbonate or ABS rubber. A soft shell container is typically made of flexible plastic films such as, but not limited to, polyethylene, polyurethane, santoprene or flexible vinyl, or combinations thereof. If a soft shell container is required to conform to a specific geometry, it may be pressurized and may additionally have a rigid supporting frame, or container, to ensure confirmation to the required geometry. The combination soft shell, hard shell containers are typically used to form a container that varies in shape or volume during a use cycle.
The entire bioreactor, including the container, ports and mixing mechanism, are typically sterilized prior to use by well-known sterilization technology such as, but not limited to, high temperature steam or gamma ray radiation. To keep the bioreactor, or mixer, sterile during the life cycle of its use, all penetrations of the containers must be sealed. Providing an adequate seal for agitation mechanisms is problematic as the agitation mechanisms typically have a driving motor external to the container and an impellor, or other agitating mechanism, internal to the container. In order to impart motion to the agitating mechanism, typically rotary motion to an impellor, the drive shaft must move relative to the opening in the container. The challenge is how to form an effective seal between the moving drive shaft and the container. The seal must be water-tight and allow many weeks of continuous operation without using lubricants that may contaminate the contents of the container.
In one-use mixers, or bioreactors, the challenge is made more difficult because low cost is a further, important requirement of disposable equipment. Most seals that allow rotary motion are complex and, therefore, expensive. What is needed is a simple, robust, low-cost, sealed drive that allows an external drive mechanism to provide internal agitation to the contents of a container.